Project Summary/Abstract Young adult veterans from the wars in Iraq and Afghanistan represent a population at risk for heavy drinking and resulting long-term problems from use. Unfortunately, few seek treatment for alcohol concerns. The objective of this planned research is to more fully test the efficacy of a very brief, inexpensive, single-session, and web-delivered personalized normative feedback (PNF) intervention developed by our team and evaluated in a successful pilot R34 study to prevent alcohol misuse and associated negative consequences, as well as increase behavioral health treatment seeking behaviors among a difficult to reach and treatment resistant veteran population. We expand on our successful pilot work by (1) building a large publicly available database of young veteran drinking and treatment seeking norms, (2) focusing on reaching veterans who have recently separated from the military and drink heavily but who have not recently sought any behavioral health treatment, (3) evaluating how an enhanced intervention offering PNF content specifically related to treatment seeking affects preparatory behaviors and actual treatment initiation, and (4) testing hypothesized mediators and moderators of intervention drinking and treatment initiation outcomes relevant for this population. In Aim 1, we add to our large database of drinking norms for the population by collecting drinking and treatment seeking information from veterans underrepresented in the pilot, such as female veterans (total sample N = 2,500). In Aim 2, we then use these norms in a randomized controlled trial of the PNF intervention designed to reach heavy drinking young veterans who are not currently receiving behavioral health care (N = 800) and test if additional feedback about treatment seeking can help promote treatment initiation among this treatment resistant group. Outcomes at 3, 6, 9, and 12 months are compared for participants receiving an enhanced PNF condition (N = 400) to an attention-only control condition (N = 400). In Aim 3, we test mediators of intervention efficacy on drinking outcomes (i.e., changes in perceived norms, increases in treatment initiation) and explore moderators of outcomes to determine if the brief intervention works better for veteran participants based on age, gender, reasons for drinking (social versus coping), perceived stigma, PTSD and depression symptoms, and solitary drinking. The proposed research offers significant methodological advancements to current PNF approaches by targeting a comorbid population with unmet behavioral health needs. The public health impact of the approach is promising as the intervention is hosted entirely on the Internet and can reach veterans outside of treatment settings. The self-sustaining program uses limited time and personnel and is available on mobile phones and tablets. The intervention can reach a large population resistant to conventional therapies and functions as a stand-alone approach to prevent drinking consequences and promote treatment initiation early, before alcohol misuse and comorbid problems become chronic.